Patent GB-190007471-A (GB)
Title: Improvements in Electric Telegraphy
Inventor: BROWN SIDNEY GEORGE
Filed: 1900-04-23
Granted: 1901-07-23
Abstract: 7471. Brown, S. G. April 23. Telegraphs.-Relates to arrangements and systems of diplex telegraphy capable of being duplexed and thus converted to quadruplex. The transmitting - a p p a - ratus may be run synchronously, either by a phonic wheel or other electrical or mechanical motor, or the signals may be allowed to overlap, in which case the receiving - apparatus is provided with rotating curbing relay arms by which a varying resistance is thrown into the local correcting - circuit for the purpose of varying the local correcting- current in accordance with the varying signal current due to overlapping. The signals may be received either by a siphon recorder, in which case the curve traced by the pen will be a compound curve representing the superposition of the two separate signal curves, and to assist in analysing this curve transverse lines are drawn across the tape so as to divide the curve into signal units. Longitudinal lines are also employed representing units of battery strength. Instead, however, of receiving as a compound curve, the signals may be analysed by employing a rotating drum relay such as described in Specification No. 1434, A.D. 1899, and separating the signals out to the distinct receivers. In one form described, the double-punched tape is passed through the receiver at double rate, the receivers recording both messages on one tape. Fig. 1 shows the arrangement for diplex working, in which there are two transmitters A, B, driven synchronously and provided with batteries A', B<1> having strengths preferably of 3 to 1. At the receiving-station the coil D is preferably double-wound, and has its line coil shunted by an induction I<1>. The tongue d normally rests on an insulating-division e, white the other divisions of the drums are connected up to the relay magnets F, G, H, I, and to the rotary clutch relay P, such as described in Specification No. 17,786, A.D. 1899. This clutch relay is preferably kept in unison with the transmitter by means of the speed control apparatus described in Specification No. 12,201, A.D. 1898. The relays F, . . . I are provided with armatures f, g, h, i, controlling the local circuits of the receivers J, K, L, M, and at the same time by means of the batteries N, O and resistances R<1>, R<2> are connected through the retardative resistances R and condensers K* to the second winding of the coil D, so that the coil D is curbed and brought back to its zero position. Quadruplexing is preferably carried out by Harwood's method of duplexing, and, when the signals overlap, the contactneedles of the automatic transmitter are provided with balanced arms and the contact-levers have returning-cams, so as to ensure the distinct transmission of two overlapping signals. The receivers may also be provided with driven snail cam mechanical relays by which the contact of the local recording-circuit is closed for a uniform period for each signal. A modified arrangement of inductance I' is also described, in which the line condenser is shunted by a variable resistance, and the inductance I<1> is arranged in series with the record coil d<1> as a shunt across the line coil of D, the main circuit of the coil d<1> being arranged not to include the inductance.